Plastic leaching chambers having an arch shape cross section are known in the art and are commonly buried within trenches that are dug into the soil. Waste water coming from a source, such as a septic tank, is typically conveyed to the first leaching chamber of a string of leaching chambers by means of an inflow pipe, wherein the waste water enters the first leaching chamber via the inflow pipe which is inserted into an opening, or hole, in the end plate or end cap of the chamber. Because the inflow pipe is often inserted into the hole in the end plate at an elevation above the soil, wherein the soil typically lies at the base level of the chamber, the water projects a short distance into the chamber. Unfortunately, as the water flows through the pipe and into the chamber, the force of the water dropping from the pipe onto the soil at the bottom of the chamber can cause erosion of the soil, thus possibly undermining the chamber over time or even causing drain holes to become clogged. One method that has been used to avoid this problem involves placing a flat stone or fabricated plate of plastic or concrete, generally called a splash plate, upon the soil so that the plate lies within the chamber vertically below the place where the inflow pipe discharges.
Some plastic end caps that are sold in commerce are sold by Infiltrator Systems Inc. of Old Saybrook, Conn. and often include such kind of splash plate, wherein a typical splash plate may be about 6 inches by 8 inches in dimension. The edge of the splash plate may have tabs that mechanically engage the base of the end cap to keep the splash plate from moving over time, such as by floating or by force of the water hitting the splash plate. For example, FIG. 1 illustrates one such splash plate 102, in accordance with the prior art, associated with an end cap 100 as disclosed in U.S. Pat. No. 7,008,138 to Burnes et al., and is referred to further hereinafter.
When the waste water flows into the chamber by gravity at a relatively low volumetric flow rate, the water tends to drop vertically downward at the entry point. In this case, the installer may be fairly confident that he knows where to position the splash plate to avoid soil erosion. However, prior art splash plates are not well suited to address the problems that exist when the waste water is sent to the chamber by means of a dosing pump. This is because the volumetric flow rate of the water from the dosing pump may vary from time to time and is typically higher than water flowing solely by gravity. This higher flow rate causes the water to project farther into the chamber and unfortunately, the location of the landing point of the water typically varies from installation to installation and from time to time during use.
In such situations, it has been found that soil erosion still occurs with the prior art splash plates because the water projected into the chamber either flows rapidly off of the splash plate and into the chamber, only partially lands on the splash plates or overshoots the splash plates altogether. This is undesirable for several reasons. First, because during erosion the soil is washed away and typically flows downstream into the chamber, the eroded soil can clog the drain holes preventing needed flow. Second, in one worse case scenario, as more and more soil at the base level of the chamber erodes, the stability of the chamber can become compromised and if enough soil erodes away, the chambers can shift. Third, in another worse case scenario, if enough soil is eroded such that the soil supporting the end cap could be undermined over time, the end cap could be allowed to shift away from the chamber.